Mailing Address:
4044 Derring Hall
Blacksburg, Virginia 24061 USA

Office: 5086 Derring Hall
Office Phone: 540.231.4147
Fax: 540.231.3386
wigginto@vt.edu

CV

Brief resesearch description: Bacterial proteins called cytochromes are responsible for direct electron transfer to mineral surfaces. My dissertation revolves around characterizing the electron transfer properties of multiheme cytochromes from Shewanella oneidensis. For example, we can prepare molecular monolayers of cytochromes adsorbed to solid surfaces and probe the way in which they mediate electron transfer (Wigginton et al, 2007a, Geochim. Cosmochim. Acta). Theoretical treatment of

single-molecule tunneling spectra demonstrates two distinct electron transfer mechanisms for two similar outer-membrane decaheme cytochromes OmcA and MtrC (Wigginton et al, 2007b, J. Phys. Chem. B). This suggests that each cytochrome may be designed to operate at different redox potentials when reducing various metal oxides (e.g. hematite). Because we still know very little about these proteins (i.e. we do not yet know their crystal structure), studying other similar proteins that have been rigorously characterized may shed additional light into the electron transfer processes at surfaces. I have now used similar techniques on a tetraheme cytochrome from S. oneidensis (STC) with a known crystal structure and am working towards combining it with molecular dynamics simulations and ab initio electron transfer calculations in collaboration with scientists at Pacific Northwest National Laboratory .

This figure is a three-dimensional STM image of MtrC molecules on Au(111). MtrC mediates tunneling current through two or more heme groups (inset) which allows for efficient electron transfer to mineral surfaces.

In addition to the above work, I am presently designing a slightly different single-molecule system using STM to probe the distance-dependent electron transfer efficiency of these same cytochromes. This becomes important at the mineral-microbe interface when cytochromes are not able to come in direct contact with a mineral but still may be able to donate electrons to the surface. For this project I am collaborating with Prof. Andrew Stack (Georgia Tech) and using his electrochemical STM.

Another project that I am involved with in collaboration with Kelly Haus is understanding how nanoparticles in drinking water samples influence toxic metal availability. We have drinking water samples from Washington D.C. that show a strong association of Pb with Fe-oxides (Wigginton et al, 2007, J. Environ. Monit.). Now we're moving on to experimental systems with Prof. Marc Edwards (Civil & Environmental Engineering) to study how various disinfectants affect Pb association with nanoparticles.

Applications and further interests: Because this research involves characterizing electron transfer processes in metal-reducing bacteria, it has exciting applications in the development of bioremediation strategies and microbial fuel cells. In addition to these research areas, I am also interested in other topics such as photovoltaic solar cells, nuclear waste management, carbon sequestration, and evolutionary microbiology.

I also have an interest in science writing and one day hope to be involved with the editorial side of science publishing. Right now I write a regular column for Geochemical News (here) and write a blog for Nature Network (here) called 'The Critical Zone.' Also, I wrote a piece for Elements magazine in early 2008 on scientific communication (pdf).